Oh, snap! A within-wing sonation in black-tailed trainbearers.

Area of Science:

• Ornithology
• Bioacoustics
• Biomechanics

Background:

• Vocalization is the primary studied sound production in vertebrates.
• Non-vocal sound production, especially in birds, is less understood.
• Trainbearer hummingbirds produce loud snaps during high-speed dives.

Purpose of the Study:

• Investigate the mechanism behind the loud snaps produced by male trainbearer hummingbirds during dives.
• Test hypotheses involving tail use or wing-striking.
• Determine the relationship between wing kinematics and sound production.

Main Methods:

• High-speed video recording of hummingbird dives.
• Detailed analysis of wing kinematics and stroke amplitude.
• Acoustic analysis of the produced snaps using sound recordings.
• Correlation analysis between wingbeats and sound events.

Main Results:

• Each snap is an acoustic couplet, with two sounds approximately 13 ms apart.
• High-speed video analysis refuted hypotheses of tail or wing-striking sound production.
• Snaps are produced by a within-wing mechanism, synchronized with a specific pair of deep wingbeats.
• A 1:1 match was observed between stereotyped deep wingbeats and snap production patterns.

Conclusions:

• The sound production mechanism in trainbearer hummingbirds is a within-wing event, not external.
• This specific wing kinematics-driven sound production may be common in other bird species.
• Further research is needed to understand the physical acoustics of this within-wing sound production.